Wipe The Slate Clean by Chris Webb - Trick

A blue backed deck of cards are shown and any card is freely chosen and signed. The card is placed into the center of the deck and in an instant all the cards have changed from blue to red backed cards except one card. Of course, this is the spectators signed card, but then for the kicker. the card's back visually changes half to red then full to red, and the card can be given out.